Bending apparatus



Oct. 6, 1970 K. B. GARNER ETAL 3,531,963

BENDING APPARATUS 2 Sheets-Sheet 1 Filed Deo. 4, 1967 FIG.

0dr. 6, 1970 K, B. GARNR EVAL 3,531,963

BENDING APPARATUS 2 Sheets-Sheet 2 Filed Dec. 4, 1967 INVENTORS KENNETH B. GARNER a|\ mw om KENNETH A. SIMONS United States Patent O 3,531,963 BENDING APPARATUS Kenneth B. Garner, Chattanooga, and Kenneth A.

Simons, Signal Mountain, Tenn., assignors to Combustion Engineering, Inc., Windsor, Conn., a corporation of Delaware Filed Dec. 4, 1967, Ser. No. 687,858 Int. Cl. B21c 51/00 U.S. Cl. 72-31 5 Claims ABSTRACT OF THE DISCLOSURE A portable tube bending apparatus mounted for readily conveyable movement on a support, the apparatus accomplishing the bending of a tube by the interaction of a grooved bending roller with a grooved quadrant die. The grooved bending roller is mounted on a linkage assembly which, in turn, is mounted for rotation about the grooved quadrant die. An hydraulic jack and cable means is specifically controllable to actuate the bending apparatus to bend a tube to a particular desired angle, the apparatus itself being used as a protractor for measuring the bend angle. The grooved bending roller is located on the linkage assembly in such a manner so that it will provide the sole clamping force necessary to hold a tube in the bending apparatus while providing sufficient bending leverage to bend the tube without distortion.

BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to the art of tube bending and more particularly to a portable tube bending apparatus.

In many areas of manufacture, it is necessary to take standard tubing lengths and bend them to arrive at a desired configuration. The conventional means of bending tubing where accuracy of bend radius, accuracy of bend angle, and control of roundness on small radius bends are required involve the use of large, stationary, relatively expensive machines. The tubing is brought to a machine, the entire tube being in a state of motion during the bending process. In the machines of the prior art, hydraulic cylinders and mechanical leveragey means have been used in an attempt to gain the necessary forces required to bend tubes of large wall thickness. Such devices, however, must be large in nature and, therefore, it is not practical to make them portable. Although there are in the field some portable tube bending devices, it has been found that these portable benders do not have suicient strength to accomplish bending of large tubes with appreciable wall thickness such as found in many areas of boiler design, for example.

Therefore, in view of the existing need for a powerful, yet portable tube bender, we have derived a simple, relatively inexpensive apparatus which has the power to bend large, thick walled tubes while easily being taken to the work. The work itself can remain stationary while the bending apparatus, which is suspended from a portable manipulator, provides the bending process motion. In our bending device, we use a grooved quadrant die mounted on a support means and a linkage rotating relatively thereabout, the linkage being rotated by hydraulic jack and cable means. On thelinkage means there is mounted for interaction with the grooved quadrant die a grooved roller which serves, as a result of its novel local location, as clamping means for the tube and also bending means therefor. To accomplish this dual function, the roller means is mounted on the linkage to significant distance greater than the distance of a coincident radius of the grooved quadrant die to the point of tangency between Patented Oct. 6, 1970 ICC a tube to be bent and the quadrant die plus the radius of the roller means. In this manner, when the roller contacts the tube to be bent in the device, it will be at some point to the right (or left) of the point of tangeucy of the tube to the grooved quadrant die. The roller, therefore, will serve to clamp the tube (necessary to maintain roundness) and at the same time will have a significant bending moment arm rather than deriving its moment arm from a crushing of the tube as is the case with the present tube bending devices.

The grooved quadrant die support means has an angle measuring scale attached thereto; and the linkage means has a corresponding angle indicating pointer. When the hydraulic jack and cable means are actuated to perform the bending function by rotating the linkage means about the grooved quadrant die, the pointer on the linkage means will traverse the scale on the support means and the exact angle of bend may be determined at any time. By a unique control for the hydraulic jack and cable means, the jack may be actuated to bend the tube to an approximate angle to which it is desired to bend the tube. Pressure in the jack may then be released to the extent that strain in the tube will be relaxed and an exact reading of the amount of bend of the tube may be determined. If the angle of bend has not been fully accomplished, the jack may then be reactuated to complete the desired degree of bending. When the desired angle is accomplished, total pressure may then be relieved from the jack so that the tube may be easily removed from the bending device.

Another unique feature of our invention is the use of a wire cable means in cooperation with the hydraulic jack to actuate the bending apparatus. The cable means is attached at both ends to the ram 0f the hydraulic jack and entrained at its mid-portion over a transverse sheave mounted on the grooved quadrant die support means while being guided by guide sheaves also located on the support means. This arrangement results in an automatically balanced application of force reaction on the linkage means to which the hydraulic jack cylinder is attached. While the cable unwraps from the guide sheaves, it is kept co-axial with the jack and its line of pull is always tangential to an imaginary circle about the axis of the grooved quadrant die support means so that the torque is equal at every angle. This organization of elements develops the maximum bending force output for a given unit of space.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall perspective of the portable bender of this invention showing a tube bent to greater than FIG. 2 is a detailed plan view of the particular bending apparatus with portions broken away for clarity;

FIG. 3 is a sectional view along line 3-3 of FIG. 2; and

FIG. 4 is a sectional view along line 4--4 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters are used to designate like elements, FIG. 1 shows the tube bending apparatus of our invention, generally designated 10. Crane hook 12 carries a crane eye 14 which is used in turn to carry the portable boom means 16. The crane eye 14 is attached by supports 18 to an overhead suspension boom 20 of the portable boom means 16. The overhead suspension boom 20 is supported by an upright boom support 22. Cable 24 entrained on pulleys 26 mounted on a trolley carries the tube bending support member 30. The cable 24 is lxed at one end to the suspension boom 20 and at the other to a counterweight 28 which serves to balance the weight of the tube bending apparatus and thus enable it to be readily positioned by the operator.

A yoke means 34 to constrain a tube T to be bent is mounted by means of a pin 36 to a grooved quadrant die support means 40. A main pin 46 extends through support means 40 at the central axis thereof. A grooved bending roller 42 is mounted on linkage assembly 44 which is supported on main pin 46. Attached to the linkage assembly 44 at jack mounting portion 62 is the cylinder of an hydraulic jack 48. A flexible hydraulic hose is attached at one end to any hydraulic pump 52 and at the other end to hydraulic jack 48.

As best seen in FIG. 2, the hydraulic jack 48 has therein an hydraulic piston 54 and ram 56, the ram 56 terminating at ram head 58. Attached to the ram head 58 on either side thereof (see FIG. 4) is a wire cable 60. The wire cable 60 passes through jack mounting means 62 and is guided by guide sheaves on support means 40 while being entrained at its mid-portion about transverse sheave 64 also mounted on the support means. Guide sheaves 65 keep the wire cable 60 coaxial with hydraulic jack 48.

On the support means 40, adjacent linkage assembly 44, is located an angle indicating scale 66. An angle indicating pointer 68 is attached to the linkage assembly 44 in such a manner so as to indicate a reading on the angle indicating scale 66, for determining the angle of tube bend. A control means 70 is attached to hydraulic pump 52 in order to control the operation of hydraulic jack 48. The control means in cooperation with the angle indicating means (66, 68) is operated by the novel method explained hereinbelow to bend a tube to an exact bend angle as desired.

Referring now to FIG. 3, it can be seen that grooved quadrant die support means 40 carries a grooved quadrant die 71 at an outer portion thereof while at its central axis there is located a bearing 78. Main pin 46 is supported by the bearing 78. The linkage assembly 44 is mounted for relative rotational movement with main pin 46 about support means 40. The linkage carries a roller shaft 80 to support the grooved bending roller 42. The roller shaft 80 is located on the linkage assembly 44 a distance C from the axis of the support means 40. Distance C is determined as follows. 'The linkage assembly 44 contains a portion 45 located on the extension of a line coincident with a radius to the point of tangency which a tube to be bent will make with the grooved quadrant die 71, the extension being of a length greater than the radius of the grooved roller 42. The roller shaft 80 is mounted at the end of this extended portion 45 and the grooved roller 42 is in turn mounted thereon in close enough relationship to the grooved quadrant die 71 so that the clamping action therebetween necessary to maintain roundness of the tube being bent is effected, yet far enough away to develop the necessary bending leverage.

Bearings 82 and roller shaft cap 84 transversely locate the grooved bending roller 42 relative to the stationary grooved quadrant die 71. It is noted that the grooved bending roller 42 and grooved quadrant die 71 are readily replaceable with similar members of varying size to accommodate bending of different size tubes.

Spiral return spring 86 is fastened at one end 88 to support means 40 and at the other end 90 to linkage assembly 44. The purpose of spiral return spring 86 is to return linkage assembly 44 to its original position after a tube is bent as explained hereinbelow. The grooved quadrant die support means 40 is connected to the tube bending apparatus support 30` by means of a suspension yoke and swivel 92. By loosening clamping nut B of the suspension yoke and swivel 92, the grooved quadrant die support means 40 may be adjusted about the axis A to bend a tube at any angle.

With the invention thus described, the operation is as follows. By means of a suitable overhead crane, the portable boom 16 may be taken to the location of the desired tube to be bent. By benet of the counterweight 28, the operator may easily provide nal adjustment of the tube bending apparatus 10 by hand. By loosening clamping nut B, the suspension yoke and swivel 92 can be rotated about axis A thus rotating the tube bending apparatus 10 so as to enable a tube to be bent in any desired direction. Yoke 34 is removed after first lifting out pin 36. The bending machine is then placed over the tube T during which time the tube T is loosely constrained between the grooved quadrant die 71 and grooved bending roller 42. The yoke 34 and pin 36 are then replaced. Button 72 of the control means 70` is then actuated causing hydraulic fluid to be pumped to hydraulic jack 48 through flexible hose 50. As the fluid enters the hydraulic jack 48, the piston 54 moves the ram 56 (and ram head 58) to cause tension on the wire cable 60. Simultaneously, a reactive compressive force is exerted on the jack mounting means 62. Because the length of cable 60 is fixed, the reactive force causes mounting means 62, and thus the linkage assembly 44, to rotate counterclockwise about the axis of main pin `46. The wire cable 60 unwraps from the guide sheaves 65 on support means 40 so that it is kept coaxial with the jack 48 to provide equal torque at every angle as noted above. As is well known, large forces can be developed with the use of hydraulic jacks and Wire cables. Generally speaking, more force per unit size of arrangement can be developed in this manner than with other mechanical organizations of similar size. The use of a wire cable, thus, performs a two-fold function. It enables the tube bending apparatus 10 to produce a maximum power output per unit size while creating a balanced torque at every bending angle. By the use of cables, therefore, we are able to keep the device small and thus portable yet develop a sufficient force to bend large, thick- Walled tubes.

The bending roller 42 is carried counterclockwise about the main pin 46 with the linkage assembly 44 and interacts with grooved quadrant die 71 causing the tube T to be bent on a radius corresponding to that of the grooved die 71. By locating the roller 42 in the manner as explained above, we are able to maintain the shape of the tube to be bent while at the same time accomplishing a clamping action upon the tube T between the roller 42 and the grooved quadrant die 71. Such clamping action, as noted above, is needed to control the roundness of the tube being bent. Such action is provided on conventional prior art bending machines by means in addition to the bending means; no such additional means is here required.

The angle indicating pointer 68 is observed during bending; and when the desired angle of bend is reached as determined on the angle indicating scale 66, the button 72 is released. The hydraulic pressure will cease to build up thus stopping the bending action, but the hydraulic pressure will not be released. The second button 74 will then be pushed causing sufficient pressure to be released allowing the tube to spring back a few degrees to a position wherein the strain in the tube is released. The pressure remaining in the jack 48 will keep the roller 42 firmly against the tube T. 'Ihe actual angle of bend may then be read; and if insufficient, the button 72 can be pushed again to complete the bend to the desired angle. In the above manner the bending apparatus itself is used as a protractor enabling the angle of bend to be accurately measured while the tube remains in position for corrective bending.

Once the desired angle of 'bend is obtained, a button 76 is then pushed releasing all hydraulic pressure. Spiral return spring 86, connected between support 40 and linkage assembly 44 and put in tension as a result of relative movement therebetween, causes the linkage to return to its initial position (as shown in FIG. 2) upon the release of hydraulic pressure. Yoke 34 may then be removed by pulling pin 36 and the tube is then free to be easily removed. The bending machine may then be moved on to the next tube to be bent.

As shown in FIGS. 1 and 2, an additional roller 94 may be provided if so desired. The purpose of the additional roller 94 is to give a greater leverage arm for bending extremely large, thick-walled tubes over that obtained by roller 42. This additional roller, however has been found necessary only in limited circumstances.

Thus it can be seen that we have derived a portable bending device with several novel features. By the use of hydraulic jack and cable means and their unique arrangement, we are able to generate suicient power to control the shape of small radius bends on large, thickwalled tubes while retaining the apparatus of a suiciently small size to enable it to be made portable. By the particular location of the grooved bending roller, we are able to clamp the tube, thereby eliminating the need for additional clamping structure, while at the same time developing a sufcient bending moment arm to prevent crushing of the tube during bending. We also provide a unique measuring system and bending method which permits simple, accurate determination of the bend angle by means of the bending apparatus itself while the tube remains therein and is still in position for corrective bending.

While we have illustrated and described a preferred embodiment of our invention, it is to be understood that such is merely illustrative and not restrictive and that variations and modilications may be made therein without departing from the spirit and scope of the invention. We therefore do not wish to be limited to the precise details set forth but desire to avail ourselves of such changes as fall within the purview of our invention.

We claim:

1. A portable tube bending apparatus comprising: a portable boom means; a tube bending means; pivotal connecting means for connecting said tube bending means to said portable boom means for universal movement with respect thereto; an angle indicating means mounted on said tube bending means; an hydraulic jack and cable actuating means operatively connected to said tube bending means; control means for said actuating means whereby said tube bending means may be actuated to bend a tube to a desired angle as indicated by said angle indicating means, said control means then releasing said actuating means only to the extent that strain in said tube will be released, and said control means completely releasing said actuating means upon reaching the desired degree of tube bend.

2. A portable tube bending apparatus as claimed in claim 1 wherein said tube bending means comprises a main mounting pin, a relatively stationary grooved quadrant means carrying said main mounting pin, a linkage assembly, a bending member mounted on said linkage assembly, said linkage assembly being mounted on said main mounting pin whereby it may be rotated about the axis of said pin by said actuating means.

3. Apparatus as recited in claim 2 wherein said hydraulic jack and cable actuating means comprises an hydraulic ram and cylinder and a wire cable, said cylinder portion being iixed to said linkage assembly, a xed means mounted on said stationary quadrant means, said wire cable being attached between said hydraulic ram and said fixed means.

4. Apparatus as recited in claim 3 wherein said lixed means includes a sheave, said wire cable being iixed at both ends to said hydraulic ram and having its mid-portion entrained about said sheave.

5. Apparatus as recited in claim 2 wherein said bending member is a grooved roller, and said linkage assembly includes a portion located on the extension of a line coincident with a radius to the point of tan-gency which a tube would make with said grooved quadrant means, said extension being of a length greater than the radius of said grooved roller, said grooved roller being mounted on the outer end of said extension.

References Cited UNITED STATES PATENTS 2,349,525 5/1944 St. Clair 72-36 3,190,105 6/1965 Strybel 72--217 3,276,235 lO/l966 Stanley 72-32 2,871,909 2/1959 Bower 72-321 361,398 4/1887 Daniels 72-217 FOREIGN PATENTS 642,905 6/ 1962 Canada. 618,737 3/1927 France. 1,020,508 2/1953 France. 29/ 2629 Japan.

RICHARD I. HERBST, Primary Examiner r M. I. KEENAN, Assistant Examiner U.S. Cl. X.R. 

